As a materials science expert with a focus on the interaction between metals and the human body, I can provide a detailed explanation on whether brass can cause one's skin to turn green. The concern arises from the chemical reactions that can occur when certain metals come into contact with the skin, particularly sweat, which contains salts and can accelerate the corrosion process of some metals.

Brass is an alloy made primarily of copper and zinc, with varying proportions of these elements depending on the type of brass. The two main types of brass are yellow brass, which has a higher zinc content, and red brass, which has a higher copper content. The properties of brass, including its reactivity with the skin, depend on these proportions and any additional elements that may be present.

Copper, one of the main components of brass, is known to react with the salts in sweat to form copper salts. Over time, this can lead to a greenish patina on the surface of copper and brass objects, which is often referred to as "verdigris." This patina is a layer of copper carbonate or copper chloride, formed by the oxidation of copper when exposed to air or moisture.

When brass comes into contact with the skin, especially in areas where there is a high concentration of sweat, it can cause a similar reaction. The salts in the sweat react with the copper in the brass, leading to the formation of copper salts. These salts can be absorbed by the skin, resulting in a greenish discoloration. However, this is generally a temporary effect and should not cause any long-term harm to the skin.

It's important to note that enameled or oxidized copper products are less likely to cause this issue. Enamel is a type of coating that can be applied to copper and brass to prevent direct contact with the skin and reduce the likelihood of a reaction. Oxidation treatments can also be used to create a stable, protective layer on the surface of the metal, which can help to minimize the potential for skin discoloration.

However, one should be cautious with antique plating. Antique plating is a decorative technique that involves applying a thin layer of a different metal, often silver or gold, over the brass to give it an aged or distressed appearance. This layer can wear off over time, exposing the underlying brass and increasing the risk of a reaction with the skin.

In conclusion, while brass can potentially cause a temporary green discoloration of the skin due to the formation of copper salts, this effect is generally harmless and can be mitigated through the use of protective coatings or treatments. It's always a good idea to clean brass jewelry regularly to reduce the buildup of salts and minimize the potential for skin discoloration.

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Enameled or oxidized copper is generally fine, though be cautious of --antique-- plating, as I mentioned under Brass and Bronze. It does, of course tarnish easily, and expect it to turn your skin green.read more >>